Wound treatment and selective help in a termite-hunting ant.

Open wounds are a major health risk in animals, with species prone to injuries likely developing means to reduce these risks. We therefore analysed the behavioural response towards open wounds on the social and individual level in the termite group-hunting ant Megaponera analis During termite raids, some ants get injured by termite soldiers (biting off extremities), after the fight injured ants get carried back to the nest by nest-mates. We observed treatment of the injury by nest-mates inside the nest through intense allogrooming at the wound. Lack of treatment increased mortality from 10% to 80% within 24 h, most likely due to infections. Wound clotting occurred extraordinarily fast in untreated injured individuals, within 10 min. Furthermore, heavily injured ants (loss of five extremities) were not rescued or treated; this was regulated not by the helper but by the unresponsiveness of the injured ant. Interestingly, lightly injured ants behaved 'more injured' near nest-mates. We show organized social wound treatment in insects through a multifaceted help system focused on injured individuals. This was not only limited to selective rescuing of lightly injured individuals by carrying them back (thus reducing predation risk), but, moreover, included a differentiated treatment inside the nest.

Time-optimized path choice in the termite-hunting ant Megaponera analis.

Trail network systems among ants have received a lot of scientific attention because of their various applications in problem solving of networks. Recent studies have shown that ants select the fastest available path when facing different velocities on different substrates, rather than the shortest distance. The progress of decision making by these ants is determined by pheromone-based maintenance of paths, which is a collective decision. However, path optimization through individual decision making remains mostly unexplored. Here, we present the first study of time-optimized path selection via individual decision making by scout ants. Megaponera analis scouts search for termite-foraging sites and lead highly organized raid columns to them. The path of the scout determines the path of the column. Through installation of artificial roads around M. analis nests, we were able to influence the pathway choice of the raids. After road installation, 59% of all recorded raids took place completely or partly on the road, instead of the direct, i.e. distance-optimized, path through grass from the nest to the termites. The raid velocity on the road was more than double that on the grass, and the detour thus saved 34.77±23.01% of the travel time compared with a hypothetical direct path. The pathway choice of the ants was similar to a mathematical model of least time, allowing us to hypothesize the underlying mechanisms regulating the behavior. Our results highlight the importance of individual decision making in the foraging behavior of ants and show a new procedure of pathway optimization.

Fluid dipping technology of chimpanzees in Comoé National Park, Ivory Coast.

Over a 6 month period during the dry season, from the end of October 2014 to the beginning of May 2015, we studied tool use behavior of previously unstudied and non-habituated savanna chimpanzees (Pan troglodytes verus) living in the Comoé National Park, Ivory Coast (CI). We analyzed all the stick tools and leaf-sponges found that the chimpanzees used to forage for ants, termites, honey, and water. We found a particular behavior to be widespread across different chimpanzee communities in the park, namely, dipping for water from tree holes using sticks with especially long brush-tip modifications, using camera traps, we recorded adults, juveniles, and infants of three communities displaying this behavior. We compared water dipping and honey dipping tools used by Comoé chimpanzees and found significant differences in the total length, diameter, and brush length of the different types of fluid-dipping tools used. We found that water dipping tools had consistently longer and thicker brush-tips than honey dipping tools. Although this behavior was observed only during the late dry season, the chimpanzees always had alternative water sources available, like pools and rivers, in which they drank without the use of a tool. It remains unclear whether the use of a tool increases efficient access to water. This is the first time that water dipping behavior with sticks has been found as a widespread and well-established behavior across different age and sex classes and communities, suggesting the possibility of cultural transmission. It is crucial that we conserve this population of chimpanzees, not only because they may represent the second largest population in the country, but also because of their unique behavioral repertoire.

Only distance matters - non-choosy females in a poison frog population.

BACKGROUND: Females have often been shown to exhibit preferences for certain male traits. However, little is known about behavioural rules females use when searching for mates in their natural habitat. We investigated mate sampling tactics and related costs in the territorial strawberry poison frog (Oophaga pumilio) possessing a lek-like mating system, where both sequential and simultaneous sampling might occur. We continuously monitored the sampling pattern and behaviour of females during the complete period between two successive matings. RESULTS: We found no evidence that females compared males by visiting them. Instead females mated with the closest calling male irrespective of his acoustic and physical traits, and territory size. Playback experiments in the natural home ranges of receptive females revealed that tested females preferred the nearest speaker and did not discriminate between low and high call rates or dominant frequencies. CONCLUSIONS: Our results suggest that females of O. pumilio prefer the closest calling male in the studied population. We hypothesize that the sampling tactic in this population is affected by 1) a strongly female biased sex ratio and 2) a low variance in traits of available males due to strong male-male competition, preventing low quality males from defending a territory and mating.

Evolutionary change from induced to constitutive expression of an indirect plant resistance.

Induced plant resistance traits are expressed in response to attack and occur throughout the plant kingdom. Despite their general occurrence, the evolution of such resistances has rarely been investigated. Here we report that extrafloral nectar, a usually inducible trait, is constitutively secreted by Central American Acacia species that are obligately inhabited by ants. Extrafloral nectar is secreted as an indirect resistance, attracting ants that defend plants against herbivores. Leaf damage induces extrafloral nectar secretion in several plant species; among these are various Acacia species and other Fabaceae investigated here. In contrast, Acacia species obligately inhabited by symbiotic ants nourish these ants by secreting extrafloral nectar constitutively at high rates that are not affected by leaf damage. The phylogeny of the genus Acacia and closely related genera indicate that the inducibility of extrafloral nectar is the plesiomorphic or 'original' state, whereas the constitutive extrafloral nectar flow is derived within Acacia. A constitutive resistance trait has evolved from an inducible one, obviously in response to particular functional demands.

Status and distribution of Comoé Chimpanzees: combined use of transects and camera traps to quantify a low-density population in savanna-forest mosaic.

The West African chimpanzee is critically endangered (CR). From 1990 to 2007, Ivory Coast lost 90% of its population to habitat destruction and poaching. In order to effectively implement conservation measures, we need to determine the status of any remaining populations in the country. The chimpanzee population of Comoé National Park (CNP) was assumed to have been severely depleted following the politico-military crisis of 2002-2011. Surveys in 2007, 2010, 2012, and 2014 failed to find significant evidence of chimpanzees in the park, leading managers to believe that no sustainable population was left. To evaluate status and distribution of chimpanzees in CNP, in 2015 we conducted a stratified survey in our study area in the southwest of the park. Over the next 3 years, we conducted recce walks in the north, east, and center of the park, and in 2017 we collected additional data on distribution of chimpanzees during the full park survey for elephants. Additionally, for the first time in northern Ivory Coast, we carried out a local nest decay study. In our main study area, we estimated a density of 0.14 weaned chimpanzees/km2, with an abundance of 127 (92-176) weaned chimpanzees, representing a sustainable population in CNP. We identified 123 individual chimpanzees via parallel camera-trap survey. We discovered a resident chimpanzee population to the east of the Comoé River, an area previously assumed devoid of chimpanzees. This study confirms the viability of a population key for the conservation of Western chimpanzee. We stress the importance of concentrating stratified surveys in potential wildlife habitat to determine the distribution of this and other cryptic threatened species.

The importance of environmental heterogeneity for species diversity and assemblage structure in Bornean stream frogs.

1. Several hypotheses have been proposed to explain the structure of multi-species assemblages. Among these, abiotic environmental factors and biotic processes are often favoured. Several recent studies examining anuran communities identified environmental factors to be only of minor importance in the composition of leaf-litter and canopy assemblages in pristine forests. Instead, spatial effects and spatially structured environments were considered more important. 2. In this study, we investigated whether these findings could also be confirmed for very heterogeneous stream habitats in the primary rainforest of the Ulu Temburong National Park, Brunei Darussalam. We thus investigated anuran assemblage compositions on 50 stream sites with regard to environmental and spatial influences. 3. Cross-product correlations indicated that both factors (spatial and environmental parameters) determined assemblage composition of anurans. Environment itself may be spatially structured, yet this interrelation did not contribute to the explainable variation of frog community compositions within the study area. 4. Detailed analyses of the environmental parameters with nonmetric multidimensional scaling revealed that community structure was mostly affected by three major environmental characters: stream turbidity, river size and the density of understorey vegetation. Based on these habitat characteristics, we assigned species to three distinct habitat guilds. 5. The results underline the importance of riparian habitat heterogeneity in pristine forests in structuring anuran assemblages. We conclude that different anuran assemblages, that is, leaf litter, canopy and stream communities, follow different assemblage rules and thus are not directly comparable.

The disregarded West: diet and behavioural ecology of olive baboons in the Ivory Coast.

Despite living under environmental conditions considerably distinct from those of savannah baboons (Papio spp.) in East and southern Africa, very little is known about western Papio populations. We monitored the abundance and group sizes of olive baboons (P. anubis) in the savannah-forest mosaic of the Comoé National Park, northern Ivory Coast, and observed 2 habituated groups of different sizes. Against expectations for the kind of habitat, the individual density was low, yielding only 1.2 baboons/km(2). The groups were small, comprising on average 15 individuals, and the proportion of 1-male groups (50-63%) was remarkably high. One-male groups were more female biased than multi-male groups. The baboons were highly frugivorous, spending about 50% of their feeding time on fruits and seeds of at least 79 woody plant species. The 2 habituated groups had comparatively large home ranges and used forests more often than expected by random. We argue that regular subgrouping of the larger focal group and different habitat quality countervailed inter-group variations. Differences from other study sites, however, are not completely explained by current models of baboon (socio)ecology. It appears that the social organization of olive baboons is more flexible than assumed from data on East African populations.

Impact of human disturbance on bee pollinator communities in savanna and agricultural sites in Burkina Faso, West Africa.

All over the world, pollinators are threatened by land-use change involving degradation of seminatural habitats or conversion into agricultural land. Such disturbance often leads to lowered pollinator abundance and/or diversity, which might reduce crop yield in adjacent agricultural areas. For West Africa, changes in bee communities across disturbance gradients from savanna to agricultural land are mainly unknown. In this study, we monitored for the impact of human disturbance on bee communities in savanna and crop fields. We chose three savanna areas of varying disturbance intensity (low, medium, and high) in the South Sudanian zone of Burkina Faso, based on land-use/land cover data via Landsat images, and selected nearby cotton and sesame fields. During 21 months covering two rainy and two dry seasons in 2014 and 2015, we captured bees using pan traps. Spatial and temporal patterns of bee species abundance, richness, evenness and community structure were assessed. In total, 35,469 bee specimens were caught on 12 savanna sites and 22 fields, comprising 97 species of 32 genera. Bee abundance was highest at intermediate disturbance in the rainy season. Species richness and evenness did not differ significantly. Bee communities at medium and highly disturbed savanna sites comprised only subsets of those at low disturbed sites. An across-habitat spillover of bees (mostly abundant social bee species) from savanna into crop fields was observed during the rainy season when crops are mass-flowering, whereas most savanna plants are not in bloom. Despite disturbance intensification, our findings suggest that wild bee communities can persist in anthropogenic landscapes and that some species even benefitted disproportionally. West African areas of crop production such as for cotton and sesame may serve as important food resources for bee species in times when resources in the savanna are scarce and receive at the same time considerable pollination service.

Fitness related diet-mixing by intraspecific host-plant-switching of specialist insect herbivores.

Generalist insect herbivores may profit by feeding on a mixture of plant species that differ in nutritional quality. Herbivore performance can also be affected by intraspecific host plant variation. However, it is unknown whether conspecific plant individuals differ sufficiently to promote diet-mixing behavior in specialist herbivores. We experimentally tested this "specialist diet-mixing hypothesis" for specialist caterpillars (Chrysopsyche imparilis, Lasiocampidae) in a West African savanna. The caterpillars switched regularly between host tree individuals (Combretum fragrans, Combretaceae). To examine whether switching benefited caterpillar performance via diet-mixing, the caterpillars were reared either on leaves from several plant individuals (mixed diet) or on leaves from a single plant. The strongest effect of diet-mixing was found for fecundity, with females reared on a mixed diet laying significantly more eggs than sisters receiving a single-plant diet. In addition, a mixed diet decreased variability in egg size and increased the growth of second-instar caterpillars. Supplementary food choice experiments were conducted to assess a potential influence of lowered host quality (induced by herbivory) on caterpillar behavior; no such effect was found. By linking intraspecific host-switching behavior and herbivore performance, this study provides new information on the relevance of intraspecific plant variation for herbivorous insects.

Clouded leopard phylogeny revisited: support for species recognition and population division between Borneo and Sumatra.

BACKGROUND: The clouded leopard (Neofelis nebulosa) is one of the least known cat species and depletion of their forested habitats puts it under heavy pressure. Recently reclassification of Bornean clouded leopards (N. nebulosa diardi) to species level (N.diardi) was suggested based on molecular and morphological evidence. Since the genetic results were based solely on three Bornean samples we re-evaluated this partition using additional samples of Bornean clouded leopards (N = 7) and we were also able to include specimens from Sumatra (N = 3), which were lacking in previous analysis. RESULTS: We found strong support for the distinction between N. nebulosa and N. diardi based on three fragments of mtDNA (900 bp) and 18 microsatellites. Forty-one fixed mitochondrial nucleotide differences and non-overlapping allele sizes in 8 of 18 microsatellite loci distinguished N. nebulosa and N. diardi. This is equivalent to the genetic divergence among recognized species in the genus Panthera. Sumatran clouded leopards clustered with specimens from Borneo, suggesting that Sumatran individuals also belong to N. diardi. Additionally, a significant population subdivision was apparent among N. diardi from Sumatra and Borneo based on mtDNA and microsatellite data. CONCLUSION: Referring to their origin on two Sunda Islands we propose to give N. diardi the common name "Sundaland clouded leopard". The reduced gene flow between Borneo and Sumatra might suggest the recognition of two subspecies of N. diardi. Based on this reclassification of clouded leopards not only species, but also the populations on Borneo and Sumatra should be managed separately and a higher priority should be placed to protect the different populations from extinction.

Saving the injured: Evolution and mechanisms.

Rescue behavior focused on injured individuals has rarely been observed in animals. These observations though are from very different taxa's: birds, mammals and social insects. Here we discuss likely antecedents to rescue behaviors in ants, like social carrying and alarm pheromones. We then compare similarities and preconditions necessary for rescue behavior focused on injured individuals to evolve across taxa's: a high value of individuals, a high injury risk and social interaction. Ultimately we argue that a similar problem, how to rescue injured group members, has led to different mechanisms to save injured individuals across different taxa.

Clouded leopards, the secretive top-carnivore of South-East Asian rainforests: their distribution, status and conservation needs in Sabah, Malaysia.

BACKGROUND: The continued depletion of tropical rainforests and fragmentation of natural habitats has led to significant ecological changes which place most top carnivores under heavy pressure. Various methods have been used to determine the status of top carnivore populations in rainforest habitats, most of which are costly in terms of equipment and time. In this study we utilized, for the first time, a rigorous track classification method to estimate population size and density of clouded leopards (Neofelis nebulosa) in Tabin Wildlife Reserve in north-eastern Borneo (Sabah). Additionally, we extrapolated our local-scale results to the regional landscape level to estimate clouded leopard population size and density in all of Sabah's reserves, taking into account the reserves' conservation status (totally protected or commercial forest reserves), their size and presence or absence of clouded leopards. RESULTS: The population size in the 56 km2 research area was estimated to be five individuals, based on a capture-recapture analysis of four confirmed animals differentiated by their tracks. Extrapolation of these results led to density estimates of nine per 100 km2 in Tabin Wildlife Reserve. The true density most likely lies between our approximately 95 % confidence interval of eight to 17 individuals per 100 km2. CONCLUSION: We demonstrate that previous density estimates of 25 animals/100 km2 most likely overestimated the true density. Applying the 95% confidence interval we calculated in total a very rough number of 1500-3200 clouded leopards to be present in Sabah. However, only 275-585 of these animals inhabit the four totally protected reserves that are large enough to hold a long-term viable population of > 50 individuals.

Frogs flee from the sound of fire.

Fire has an important role in the sensory ecology of many animals. Using acoustic cues to detect approaching fires may give slow-moving animals a head start when fleeing from fires. We report that aestivating juvenile reed frogs (Hyperolius nitidulus) respond to playbacks of the sound of fire by fleeing in the direction of protective cover, where they are safe. This is a novel response to fire not known to occur in other animals. Moreover, we identify the rapid rise-time of the crackling sound of fire as the probable cue used. These results suggest that amphibian hearing not only has evolved through sexual selection, but also must be viewed in a broader context.

Polydomy and the organization of foraging in a colony of the Malaysian giant ant Camponotus gigas (Hym. / Form.).

In Kinabalu National Park, Borneo we observed four colonies of the Malaysian giant ant Camponotus gigas in a primary forest. These predominantly nocturnal ants have underground nests, but forage in huge three-dimensional territories in the rain forest canopies. The colony on which our study was mainly focused had 17 nests with about 7000 foragers and occupied a territory of 0.8 ha. To improve observation and manipulation possibilities, these nests were linked at ground level by 430 m of artificial bamboo trail. A group of specialist transport worker ants carried food from `source' nests at the periphery to the central `sink' nest of the queen. Transport of food between nests started immediately after the evening exodus of the foragers. Transporter ants formed a physical subcaste among the minors and behaved according to predictions of the central-place foraging theory. Their load size was about five times that of the average forager and grew proportionally with head width. Longer distances were run by ants with greater head width and larger gross weight. Transporter ants that ran more often took heavier loads. Experiments with extra-large baits revealed that C. gigas used long-range recruitment to bring foragers from different nests to "bonanzas" at far distant places. The foraging strategy of C. gigas is based on a polydomous colony structure in combination with efficient communication, ergonomic optimization, polyethism and an effective recruitment system.

Diversity of ant-plant interactions: protective efficacy in Macaranga species with different degrees of ant association.

The pioneer tree Macaranga in SE Asia has developed manyfold associations with ants. The genus comprises all stages of interaction with ants, from facultative relationships to obligate myrmecophytes. Only myrmecophytic Macaranga offer nesting space for ants and are associated with a specific ant partner. The nonmyrmecophytic species are visited by a variety of different ant species which are attracted by extrafloral nectaries (EFN) and food bodies. Transitional Macaranga species like M. hosei are colonized later in their development due to their stem structure. Before the colonization by their specific Crematogaster partner the young plants are visited by different ant species attracted by EFN. These nectaries are reduced and food body production starts as soon as colonization becomes possible. We demonstrated earlier that obligate ant partners can protect their Macaranga plants against herbivore damage and vine cover. In this study we focused on nonspecific interactions and studied M. tanarius and M. hosei, representing a non-myrmecophyte and a transitional species respectively. In ant exclusion experiments both M. tanarius and M. hosei suffered significantly higher mean leaf damage than controls, 37% versus 6% in M. hosei, 16% versus 7% in M. tanarius. M. tanarius offers both EFN and food bodies so that tests for different effects of these two food rewards could be conducted. Plants with food bodies removed but with EFN remaining had the lowest mean increase of herbivore damage of all experimental groups. Main herbivores on M. hosei were mites and caterpillars. Many M. tanarius plants were infested by a shootborer. Both Macaranga species were visited by various ant species, Crematogaster spp. being the most abundant. We found no evidence for any specific relationships. The results of this study strongly support the hypothesis that non-specific, facultative associations with ants can be advantageous for Macaranga plants. Food bodies appear to have lower attractive value for opportunistic ants than EFN and may require a specific dietary adaptation. This is also indicated by the fact that food body production in the transitional M. hosei does not start before stem structure allows a colonization by the obligate Crematogaster species. M. hosei thus benefits from facultative association with a variety of ants until it produces its first domatia and can be colonized by its obligate mutualist.

On benefits of indirect defence: short- and long-term studies of antiherbivore protection via mutualistic ants.

Many plants are defended indirectly by mutualistic animals. In this field study, we investigated the efficacy of indirect antiherbivore defence in symbiotic and non-symbiotic ant-plant associations in three Macaranga species. We tested whether obligate interactions are more effective than facultative ones by comparing ant-free plants, or parts of plants, with untreated controls. All three species gained significant protection from the ants' presence. The efficacy of defence was higher in the obligate associations represented by M. triloba and M. hosei than in the facultative interaction (M. tanarius). After 40 days of ant exclusion, missing leaf area amounted to 1.7% in M. hosei (compared to 0.2% in untreated, ant-defended controls), 2.6% in M. triloba (controls 1.2%) and 4.2% in M. tanarius (controls 3.2%). In a long-term study of M. triloba and M. hosei, ant protection was orders of magnitude higher than in the short-term results. Short-term experiments obviously are unsuited to obtaining a realistic picture of the long-term efficacy of antiherbivore defence. Within 1 year, ant-free plants lost, on average, between 70% (M. hosei) and 80% (M. triloba) of their total leaf area. Both species appear to require their mutualistic ants for survival. Defence via symbiotic ants is obviously a very effective form of antiherbivore protection. Ants are highly mobile and defend preferentially young, vulnerable leaves and shoot tips, and they fulfil several functions which normally have to be provided by different chemical substances. This may be a general benefit of indirect plant defence, which makes use of "animal-specific" traits rather than intrinsic plant properties.

Nutrient availability and indirect (biotic) defence in a Malaysian ant-plant.

Tropical plants of different genera defend themselves via symbiotic ant colonies, which are housed and often nourished by their host plant. Many studies deal with the defensive effects of the ants, but none has linked the plants' investment in this type of defence to the size and defensive efficacy of the symbiotic ant colony. We show here that ant-food production by the obligate myrmecophyte, Macaranga triloba, is limited by nutrient supply. The colony size of the ants in untreated plants (which had not been affected by experiments in advance of colony collection and determination of food body production) was significantly correlated with the amount of food produced by their hosts, and the plants' level of leaf damage was significantly and negatively correlated with the number of inhabiting ant workers. Our study provides the first field data that show that nutrient availability can directly influence a myrmecophyte's investment in its ants. Further studies are needed to evaluate whether soil nutrient contents in general can be a factor that limits the ability of myrmecophytes to defend themselves indirectly by nourishing symbiotic ants.

Influence of the hypogaeic army ant Dorylus (Dichthadia) laevigatus on tropical arthropod communities.

The majority of army ant species forage hypogaeically. Due to the difficulties in observing these ants, their potential influence on hypogaeic and epigaeic arthropod communities has not yet been investigated. As the first hypogaeically foraging army ant studied in detail, we attracted Dorylus laevigatus to areas monitored for their arthropod diversity. Here, for the first time, the same sites were sampled before and after an army ant raid. Furthermore, interactions between D. laevigatus and the five most common ground-nesting ant species were noted and their life-history traits compared, allowing first inferences on possible mechanisms of their coexistence. The occurrence of D. laevigatus within a study plot had no evident effect on the number of arthropod taxa or individuals collected with epigaeic and hypogaeic pitfall traps. Likewise, juvenile arthropods, which are less mobile and thus are potentially easier prey for D. laevigatus, showed no differences in their collected numbers before and after the army ant had visited a plot. However, significantly fewer ant species were collected with hypogaeic traps after D. laevigatus had been within the study plots, indicating a possible predation of D. laevigatus especially on two Pseudolasius and one Pheidole species. The five most common ground-foraging ant species demonstrated their ability to avoid, kill, and even prey on the army ant. The reaction of Lophomyrmex bedoti towards D. laevigatus indicated the former to be a potential prey species, while Pachycondyla sp. 2 showed signs of "enemy specification." Odontoponera diversus and O. transversa actively preyed on D. laevigatus, while Pheidologeton affinis fought with D. laevigatus over resources. All ant species could co-occur with D. laevigatus at palm oil baits. Adding to the differences detected in previous studies between D. laevigatus and epigaeically foraging army ant species, the occurrence of this hypogaeic army ant seems to have less devastating effects on arthropod community compositions than those of epigaeically mass raiding species.

Quinone mixture as attractant for necrophagous dung beetles specialized on dead millipedes.

2-Methyl-1,4-benzoquinone (toluquinone) and 2-methoxy-3-methyl-1,4-benzoquinone are the most common components of defensive secretions of juliform millipedes (Diplopoda: Juliformia). A natural and a synthetic millipede-defensive secretion composed of these two substances attract dung beetles of a few Onthophagus species (Coleoptera: Scarabaeidae) that feed mainly on freshly dead millipedes. This olfactory mechanism and adaptation to the toxic effects of quinones enables them to be the first and exclusive users of this resource.